Process for preparing liquid low-salt aqueous reactive dyestuff compositions

US4581036A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Konrad Opitz · Liederbach, DE
• Heinrich Pohlmann · Kelkheim, DE
• Manfred Sittig · Kriftel, DE
• Christian Fabel · Kelkheim, DE
• Siegfried Wilhelm
• Franz Mitter · Kriftel, DE

Key dates

• Filing date: Apr 4, 1985
• Grant date: Apr 8, 1986
• Expiry date: Apr 4, 2005

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B67/0096
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

A process is described for separating sodium sulfate from aqueous solutions of certain fiber-reactive dyestuffs, which contain less than 2% by weight of chloride, by cooling down said solution to a temperature between +5.degree. C. and -15.degree. C. In the course of the cooling, the sodium sulfate precipitates in the form of the decahydrate and can be separated off in conventional manner, for example by filtration. The results obtained in this way are aqueous liquid low-salt preparations of these dyestuffs which contain less than 4% by weight of sodium sulfate.